Identification of Pseudozyma hubeiensis Y10BS025 as a Potent Producer of Glycolipid Biosurfactant Mannosylerythritol lipids

Abstract

Mannosylerythritol Lipids (MEL’s) are glycolipid biosurfactants that contain 4-O-β-D-mannopyranosyl-meso-erythritol as a hydrophilic moiety and fatty acids as a hydrophobic moiety. MEL’s are abundantly produced by several kinds of microorganism and are one of the most promising biosurfactants currently known. The search for a novel endogenous producer of MEL’s was undertaken based on the available collection of the yeast strains from the genus Pseudozyma. Using thin layer chromatography and based on morphological and molecular taxonomic analysis using the D1/D2 domains of the large subunit 26S rRNA gene, Pseudozyma hubeiensis Y10BS025 was found to be a potential producer of MEL’s from soybean oil. The structure of the major glycolipid produced by the strain was analyzed by ¹H and ¹³C nuclear magnetic resonance and was found to be similar to those of well known MEL-A, -B and -C respectively. Under improved shaking culture conditions, using yeast extract as nitrogen source and soybean oil as substrate, a maximum yield of 115±3.2 g.L^-1 of MEL’s for 8 days of fermentation was achieved. The major fatty acids of MEL’s produced by P. hubeiensis Y10BS025 were C-18 acids, considerably different from those of MEL-C produced by other Pseudozyma strains such as P. antarctica and P. shanxiensis. The main product, MEL-C produced by P. hubeiensis Y10BS025 exhibited surface-tension-lowering activity. The results demonstrated that the newly isolated P. hubeiensis Y10BS025 provided high efficiency in MEL’s production and would thus be highly advantageous in commercial production of promising biosurfactants.